John is a famous writer now. But he said he was not a 1 student when he was young. He was often late for 2 and didn't like doing his homework. Sometimes, he slept in class while the teacher was teaching. He didn't understand much, 3 he always thought he understood everything. One day the teacher 4 the students a question. "When Jack was ten years old, 5 brother Bob was twenty. Jack is fifteen now and 6 is his brother Bob? " John said, "That's easy. Bob is twice as old as Jack, so he is now thirty. " Another time, the 7 in a science class asked, "When it thunders ( 打雷 ), 8 do we always see the light before we 9 the sound?" "But, Miss," said John quickly. "don't you 10 our eyes are in front of our ears?"